Indicating gage



Feb. 24, 1959 I Q 'r. A. GREEN EI'AL INDICATING GAGE Original Filed July28, 1950 3 Sheets-Sheet l umlllllll FIG. 5

I INVENTORS THOMAS A. GREEN, HARVARD H. GIORRIE, v JACK F. SHANNONTREVOR FINK T. GREEN ET AL Feb. 24, 1959 INDICATING GAGE 5 arrests-Sheet2 Original Filed July 28, 1950 l l l l l i li|| 3 w I 5 O m s E Du V C EINVENTORS THOMAS A. GREEN,

HARVARD H. GORRIE, AND JACK F. SHANNON TREVOR FINK W 4 1.0.

Fla. 9

A RNEY Feb. 24, 1959 T. AIEREEN Em 2,874,573

INDICATING GAGE Original Filed July 28, 1950 I 5 Sheets-Sheab 3INVENTORS THOMAS A. GREEN, HARVARD H. GORRIE,

AND JACK F. SHANNON TREVOR FINK ATTOR 2,874,573 INDICATING GAGE ThomasA. Green, Willonghby, Harvard H. Gorrie, Cleveland Heights, Jack F.Shannon, Euclid, and Trevor 13 Claims. (Cl. 73-414) Our inventionrelates to measuring instruments and United States Patent particularlyto indicating pressure gages of the vertical edgewise class.

The general shape is of a relatively thin rectangle with one end or edgeof the rectangle fitted for visually observing the indicationof-measurement byhaving one or more pointers arranged to move along avertically located scale path; Preferably the unit is mounted with theindicative scale substantially flush with:a panel board, the majority ofthe unit projecting behind the panel.

Our unitary construction is not, however, restricted to verticaledgewise panel mounting. One Widely accepted usage is for table mountingon bench orconsole type control panels where the scale edge of the unitis hori zontal or at a slight inclination with the horizontal and withmost of the unit projecting beneath the bench or console top.

Furthermore, the unitary enclosed construction allows the gauging-up orstacking of numerous units with the indicative scales parallel orend-to-end. On. the other hand, the unit maybe incorporated in anassembly of metering or controlapparatus to advantage. While we havechosen to designate our invention asrelated to pressure gages, weso-name a general class without meaning to restrict the usefulness ofthe invention in the measurement of other variable quantities,qualities,

2,874,573 Patented Feb. 24, 1959 Fig. 5 is an exploded view of a portionof Fig. 1.

Fig. 6 is a view, similar to Fig. 1, of a double tube gage.

Fig. 7 is a front edge view of the assembly of Fig. 6.

Fig. 8 is a view of a portion of the assembly of Fig. 6, taken along theline 88 in the direction of the arrows.

Fig. 9 is a sectional view of the assembly of Fig. 8 taken along theline 9-9 in the direction of the arrows.

Fig. 10 is a perspective view .of a portion of Fig. 6.

Fig. 11 shows a modification of a portion of Fig. 9.

Fig. 12 is an enlarged view of an indicator pointer.

Fig. 13 is a' section of the pointer ofFig. 12, along the line 13-13, inthe direction of the arrows.

Fig. 14 is a perspective view ofa panel showing mounting possibilitiesof our gage. 1 Referring now in particular to Fig. l, we show therein aside elevational view of our preferred apparatus as embodied in what issometimes termed a vertical edgewise indicator. The housing 20 is formedas a die casting obtaining lightness, with rigidity, strength and dusttightness. The shape is in general rectangular .with a flat backmounting wall 21, top wall 22, bottom wall 24 and conditions, positions,or .the like; For example, the indicator to be described may provideavisual manifestation of the magnitude of such variables as fluid rate offlow, temperature, smoke density, static pressure, speed, the positionof an object; or the interrelation of measurable values or positionssueh as a visual comparison of fluid a rear .wall 23. The near side isvnormally. covered by a removable side plate 25 (Fig. 5') which maybeheld to the housing 20 by screws threadable into holes 26.,,Forpurposes of illustration the housing 20 of Fig. l 1 has beensectioned slightly below thegledge (Fig. 5) which Pro,- vides a restingplace for the cover 25. f; I

The housing 20 has no fixed front wall (to. the right as viewed inFig. 1) but the opening is desirably closed by a molded transparentwindow 27 which may be of glass or a clear plastic. The latter ispreferred as less susceptible to breakage through handling, vibration orshock. The window 27 is formed with along radius protrudance to theright (Fig. 1) beyond the limits of housing walls 21, 22, 24. The twosides 28 and29 of window 27 extend rearwardly to join the forward edgesof back wall 21 and of cover 25. Along the topa rearvariable.Furthermore, the indication may be of a control force or loading valueand may constitute the receiver of a fluid pressure telemetering system.m r A One object of our invention is to provide anindicating' pressuregage of unitary construction adapted for universal mounting orarrangementin multiple or with other apparatus. Another object is toprovide a miniature type of indicator for minimizingspace and weightrequirements in panel board assemblies. r

'A further object resides in providing aconstruction adapted to theready gauging or grouping of a plurality of our indicators.- a

Another object is to providean indicatingreceiver' of substantiallyuniversal adaptability to different forms of variables having widevariety of'ranges or values.

A further object is to provide an indicating pressure I gage havingimproved range andz'ero I Another object lies in the provision of anindicator having a minimum susceptibility to vibratiomfshock, or

a ship or locomotive.

ward projection 30, and along the bottom a similar projection 31, enterthe confines of the housing as shown. The projection 31 is provided.with a hole 32 which may be adapted to receive a spring end 33 as shownin Fig. 1 or in the dotted position of Fig. 4.; In similar man ner the.upper projection 30 is provided with a hole receiving a more rigidspringend 34. Figs. 1 and 2 show the window 27 inits assembled locationwith projections 30 and 31 receiving the ends 33, .34 and thus holdingthe window tightly closing the end opening formedbythe housing 20and'cover 25.

Provision is made for easy} assembly as well as for ready removal of thewindow portion 27 forfinspection and cleaning of the scale, pointer,etc. Figs. 1'a nd;2 show the window in its assembled position) Fig.4 isari enlarged detail of a lower right-hand portion of Fig.1 '1-illustrating the operation to be performed for removing or insertingwindow 27.

Referring now particularly to .Fig. 4 the dot-dash outline tothe leftshows the window structure in th assembled location asin Fig. 1. If itv. is desired 're-.

move the window structure thena lifting screw, 35 be threaded upwardlythrough the tapped hole 36 pflthe leaf spring 37 until the upper endofsorew. 35 engages the fixed lower end at rivet as." Continued'threaaifi br ictew35intowhole 36 flexes the right-hand end of springope to th ough rasp the er p i n of ind 27, to move the lowermostprojection 31 outwardly from the wall 24until the pin 34 no longerengages the upper projection 3 0 and the window 27 is completelyremoved.

It tnay be reinserted through a reverse operation of first engaging thehole in upper projection 30 with the pin 34 andthen sliding the lowerportion of the window inwardly until it completely closes the end cavityof the assembly. Thereafter a backing off of. the screw 35 allows pin33;to enter the hole 32 and lock the window in place. The screw 35 maybe left partially inserted in the cavity 3.6. or. may he removed as isshown in Fig. 1.

Referring again to Fig. 4 it .will be seen that the rivet 38 .Servesadditionally to hold the scaleplate assembly .by engaging .a projection.40 thereof. The scale plate 41 itself is curved .to anarccor'responding to the travel of the indicating pointer and may be thesame or slightly different than the outward surface arc of the window27. It isonlyessential to maintain sufficient clearance between thepointer, scale plate 41 and'inner surface of window 27, at the midtravel position of the pointer.

=The lowermost end of the scale plate 41 receives a rivet 42 holding toit a spring clip 43 efiectively spacing thezscaleplate 41 from the innerlower edge of the window housing. At the upper end of the scale plate 41a similaruspring clip 44 is provided as well as a projection 45 of the.scale plate (similar to the projection 40). The pin clip 34 as well asthe projection 45 are held by a rivet 46 to the top wall 20. I Theforwardly arched scale plate 41 is recessed along its-edgesas at 47, 48providing clearance paths for movable pointers. Centered along the arcface of the scale plate 41 is-a raised scale portion 49 upon which areengraved or painted the scale graduations. Preferably the side portions50, 51 contain information, relative to the scale graduations, ofService which may be flow, pressure, or the like; and of numerals 0, 10,20, etc. relating to the "Service and to the scale graduations.

Preferably the pointer end 52 (Fig. 2) travels over thedepres'sedsurface 50 (or 51) with clearance thereover and with itsindicating end adjacent to graduations on-the elevated portion 49. Asviewed in Fig. 1 it will be observed that the pointer 52 does not extendbeyond tha amus the surface 49 and does not in any respect ovelapthegraduations' or produce parallax in reading the rg g t In the presentembodiment illumination of the unit is accomplished by' a recessed lightbulb 53 mounted in top wall '22 behind the window 27 and scale plate 41.A reflecting surface 54 may comprise a metallic or similar plate heldinposition by the rivet 42. The plate 54 may preferably be of U-shapehaving side walls spaced from therear wall 21 and the inside of cover 25fto allow pointer travel. This substantially prevents light from'thesource 53 entering the housing surrounding shield '54 and minimizing eyeviewingof working parts of the instrument behind the shield 54 throughthe slots 47,,48. Normallylthe scalepla'te 41 may he dream translucentplastic "or similar material upon which thegraduationsand other indiciaare painted or engraved so that they will 'stand out'in contrastto thelightedscale plate itself'when the latter is illuminated by'the source53 and reflection from thesurface 54.

The light source53rnay be held in a convenientsocket assembly 55 havingterminals 56 and the assembly is re vably"mounted inaiclip 57 '(Fig;'having one or oc ng i gs 58 engagea ble with the inner sur- 7 f a'h o e59 formedfin the upper wall 22 'of the hhusing 20. assembly 'isshowrii'n Fig.1 initsnornp osi t ienlwherein the prongs 58 are'in en-j.gagement and a spring button 60 carried by the clip 57 .i thu expandehroug .a hole v61 in vthe t p o w From the assembled position (Fig. l)the assembly 53, 55, 56, 58, 60 cannot be loosened or pulled from theunit, in any direction except that shown by the arrow X of Fig. 5. Inother words, any strain on 55 or 56, as by wires or conduit, toward theobserver of Fig. 1, or away from the observer, or toward the left, willnot cause a pull-outof the assembly due ,to the gripping of wedge prongs58; ,andthose are the normal directions of undesired strains upon 55, i.e., away from the back of a panel through which the window 27 projects.Desired removal is,'h'owever,readily accomplished by pivoting theaSsemblyYoWar'dthe rear of theip anel in the direction of the arrow X(Fig. 5).

The operative 'or active element of our improved indicator isillustrated in Fig. l as a Bourdon tube 65 having one end permanentlyfastenedto a base casting or forging .66 which is in turn held by screws67 to the back 21 of the housing 20. All of the contents of the housing20are supported relative to the back plate 21 so that the cover 25 mayreadily be removed without disturbing any. of the active elements whichmay continue in operation.

The interior of the Bourdon tube 65 communicates with a passage 68 andthe lower wall 24 is provided with a clearance opening 69 to allow pipeconnection to the passage 68. i

The free end of the Bourdon tube 65 is connected through an'element 70,connecting link 71 and U-shaped member 72 to angularly position theshaft 73. The shaft 73 is pivotally supported by an assembly heldtogether by screws 81. One'of the plates has an extension 82 throughwhich screws 83 pass into base 66 providing a rigid mounting for theshaft 73. Carried by the shaft 73, in additionto the U-shaped member 72,is an enlarged hub73A and a toothed disc 79. Angular motion of the shaft73, by the Bourdon tube 65, through the agency of elements 71 and'72,'angularly-moves the elements 73A and'79. i

The pointer arm 74 has a weighted end portion 75. As shown in'Fig'. 12the pointer arm has a hole 74A clearing the shaft .73. In Fig. 3 thepointer arm 74 and weight 75 are at the right of toothed disc 79 andcarry a bracket 76'which spans the disc 79 to encircle the hub 73A onthe left-hand side of disc 79. The bracket 76 is fastened'to the pointerarm 74 by a rivet 76A entering the pointerarin 74 by way of hole 76B.

Carried by the bracket 76, and engaging with the toothed disc 79 is aworm 78'extending in a plane parallel to pointer arm 74. Turning of theworm 78 in the teeth of disc 79 angularly moves the assembly 52, 74, 75,76, 76A and' 78"around the disc 79 and shaft 73. This provides a'zeroadjustment for the pointer 52 relative t'o the scale 'g'radujations 49without movement of the shaft 73 or any of the elements which cooperateto angularly position' the shaft under the dictates of the Bourdon tube65. The bracket 76, between hub 73A and rivet 76A, locks worm 78 snuglyinto engagement with teeth 79 thereby eliminating error due toclearances required for manufacture and operation'.

Carried also by the shaft 73 is one end of a hair spring 85, the otherend being adjustably clamped as at ,86 to an'eittension of a plate 80,for taking up lost motion of theassembly.

As previously mentioned the Bourdon tube 65 angularly positions theshaft73 through theagency of an element 70, connecting link 71 andw-shaped member. Reference"'r'nay. be' had'to Figfl l which showsthisdriving system'to'larger scale and additionally shows our imp ors f g iaiti' flu The" herrilger 72' is' fastened at one cnd to the shaft 7 ati'i'tsfitbs f t l fe Xtens tj ns Pl ralityof rangehole's'90'th'roughwhich we may selectively 5 r pass one end of the link 71. A screwj91i'sthreaded through an arm of the member 72 and has its end bean ingagainst the other arm of the member in a hole or hearing dimple 72A.Adjustment of the screw 91 serves to position the holes 90 relative tothe pivot 73 andto thus vary the dimension A relative to the length B ofthe pointer arm. Thus the selective holes 90 and the adjusting screw 91provides a means for varying the ratio -of A to B and thus varying therangeof pressure which must act upon the Bourdon tube 65to accomplish apredetermined travel of the pointer 52 over the scale 49.

'Initial adjustment of screw 91 stresses the U. member 72 erably made of.020 beryllium copper wire #2 hard and with a complete loop ofapproximately Vz'fin diameter.

As shown in Fig. 3 the cross-over ends at 360 are spaced to preventrubbing friction.

Shaping the link 71, as shown in Fig. 11, both as a spring-like loop andwith a desired location of the center of gravity, has been found to bethe most desirable constructional arrangement to minimize adverseeffects of vibration, shock,,inertia, harmonics, and, the like effectsbetween the Bourdon tube and the various elements connected theretothrough the agency of v the link 71.

Furthermore, the construction is preferred where the unit is to be,subjected to pitch and roll or sway conditions which accentuate inertiaeffects. For some ranges or conditions we may form link 71 as a straightlink'or in other desired configuration.

At this point we may observe that the system. being described is equallyapplicable to the measurement and indication of .either positivepressures or of negativepressures. In the latter case it may bedesirable to turn the unit upside down and reverse the scale which wouldthen he graduated from zero to whatever negative pressure were desiredfor total movement of the pointer 52.

' Fig. 10 shows to somewhat enlarged scale the stop system for Bourdontubetravel. Fig. 1, having a'single Bourdon tube, uses the same generalarrangement. Stop plates 100, 101 are identical and interchangeable. The

plate is provided with a slot 102 and screws 103 adjustably fasteningthe plate to the back 21 of the housing 20, Each of the plates, at itsleading edge, is. provided with an upturned stop portion 104. A similarstop portion 105 is staggered somewhat relative to portion 104..

The element 70 is shaped as is shown in Fig. 10 and is reversible andinterchangeablefor use on either of two Bourdon tubes. It is ofrelatively stiff material and form is provided as assembly withaninitial bending to provide the basic zero adpustmentgtortake care ofvariations, in the length of the. Bourdon tube and link and to maintainangularity of arm 74. r i As may be seen in Fig. '10 the element 70 hasa channel shaped end projectingas at 106, 107 beyond the cross-sectionof the Bourdon tube. The central portion of the channel sectionconfinesand seals the end of the Bourdon tube as well as comprising asoild driving con:- nectionbetween the movable end of the Bourdon 'tubeand the link 71. Considering the'innermost Bourdon tube (Fig. 10) theextension 107 m'aytriavel only between stops 104, 105" which are.respectively adjustable byscrews 103. t On the other" hand, theoutermost Bourdon tube 65 is limited in the travel of its free end byextension: 107 engaging sto ps 105,.104'.: The staggered relation of thespans between these pairs'of stops is due I to the fact that theextension 107" travels a different path than the extension 107.

Under normal assembled operation the extensions 107, 107' may movefreely at small clearance with the inner surface of the back 21 whilethe extensions 106, 106' may move freely at small clearance with theinside of the cover plate 25. The extensions 107, 107, 106 and 106'permit however only a relatively small sideways whip or motion of thefree end of the Bourdon tubes before such motion is stoppedby engagementof said extensions with the back wall 21 or with the plate 25. At thesame time the stops 104, 105, 105, 104' not only limit the total travelalong arcuate paths of the extensions 107, 107' but tend to preventextreme whip or similarmotion of the Bourdon tube which might otherwiseseriously damage the parts driven thereby.

Reference may now be had to Fig. 12 which shows to enlarged scale thepointer assembly comprising the pointer arm 74 having at the right-handend the pointer 52. From the pointer,-to some location C, the pointerarm 74 is ribbed for strength against whipping and twisting. It issomewhat tapered from the pointer 52 to location C with the widestportion of the taper near the pointer 52. We have found it quitedesirable to so construct the pointer arm 74 providing progressivelygreater cross-sectional weight away from the pivot hole 74A toward thepointer 52.

Fig. 13 shows a cross-section of the pointer arm 74 at the line 13-13 ofFig. 12 and it will be seen that the arm is bent over to channelshape atapproximately the location C, toward the pivot hole 74Aand in fact alongboth sides of the head of the assembly to some location such as DD.Adjacent the location D--D a small weight 75 is fastened to the head ofthe pointer arm. As previously mentioned the head of the assembly isprovided with a clearance hole 74A which freely encloses a hub of theshaft 73; and is also provided with a hole 76B for receiving the rivet76A. We have found that it is desirableto carry the channelcross-sectional shape past these two holes to the left to some locationDD to give transverse strength against shock, whip, and the like andprotect against the possibility of the localized 'weight 75 bending thehead which is normally of rather thin metal. As mentioned the arm 74 istapered in an increasing direction from near the pivot hole 74Aoutwardly to the pointer 52 with considerable weight moment toward thepointer end as compared to the moment arm of the weight 75. Theincremental weight is low along the pointer arm but the moment is high.The entire pointer structure as shown in Fig. 12 provides what we Afterthe pointer arm assembly is statically and dy-. namically balanced it ismounted in the unit, and, with. the unit in a vertical position (Figs. 1and 2) the pointer The hairspring will remain in any given position.isthen given an initial bias such that the pointer 52: rests at itslowermost travel position (opposite zero). which is actually about onep. s. i. above zero pressure (atmospheric) within the Bourdon tube.Under this bias condition the hairspring is fastened as at 86 and thelink 71 should,just fit the distance between holes 90.

The Bourdon tube elements 65, 70 are not balanced and are subjecttovibration, harmonics, etc. On the otherhand the pointer assembly isbalanced. It is this balance, plus the loop link 71, which preventsundesired movements of the Bourdon tube end from being transmitted to,and observed at, the pointer 52. The flexing of the loop 71 allows theBourdon tube which is unaamm 7 balanced to move or vibrate withoutafifectingthe pointer which is'balancedl' While we have described insome detail the structure of Fig. 1 in illustration of a' single Bourdontube indicator, we have shown in' other figures ofthe drawing thearrangement of a double pointer indicator whose edge face may besimilar-to" that shown in- Fig. '7.' Fig; 6 shows an inner Bourdon tube65' in addition to the structure of Fig. 1. The general arrangement ofdriving and adjustment elements is the same for both Bourdon tubesystems and the majorityof the parts'are interchangeable or reversibleas the case may be. Fig. 10, previously referred to, shows to enlargedview the stop system for the two tubes.

Fig. 8 illustrates a combining'of two sets of theparts described inconnection with Fig.- 3, while Fig. 9 shows a section through Fig. 8along the line 99-. It will be apparent from the'study of these drawingsthat the unit is readily adapted to single pointerindicati'on or todouble pointer indicationand furthermore it will be observed that theBourdon tubes may be subjected to either plus or minus pressures,.itbeing only necessary toproperly arrange the zero location and the scalegraduation.

Fig. 14 has been added to indicate the versatility of location andmounting of our improved indicator upon panel board structure; At 110 weindicate the vertical edgewise scale mounting of the unit on-thevertical front face of a panel 111; at 112 the multiple side-by-sidemounting of a plurality of indicators on the same vertical panel face;at 113 the side-by-side gauging, and at 114 the end-to-end gauging, of'a plurality of our indicators mounted on the horizontal or inclinedbench board or console surface 115 of a panel structure. These areindicative only of various mounting arrangements to which our indicatorsare adaptable. Itemphas'izesthat the assembly may be mounted'in anyplane'or direction without affecting the normal operation of theworkingparts.

This application is a continuation of our'co-pending application SerialNumber 176,382, filed July 28, 1950', now abandoned.

What we claim as new and desire to secure'by Letters Patent of theUnited States, is: 1

1. In a measuring instrument for visually advising the value of avariable measurement, position, or the like; a relatively thinrectangularly shaped housing having'an open front end wall, a removablewindow closely filling the opening, a scale plate located'within thehousing behind the window for observation therethrough, said scale platesubstantially filling the opening and bowed to a long radius toward thewindow, thescale plate having graduations or other indiciarepresentative of the'desired measurement, a shaftmounted pointer.having along radius arm with the pivot axis near the rear interior wallof the housing, the pointer arranged to move-over the visual length ofthe scale plate in cooperation withthe indicia thereon, the scale platehavingclearance with a side wall of the housing through which clearancethe pointer arm is movable about its pivot, a pressure re: ceivingBourdon tube having one end rigidly mounted to the interior of thehousing and'having a free end movable in the plane of pointer armtravel, and a driving connection from said Bourdon tube free end toangularly position said pivot shaft, said driving connection including aspring wire formed with a 360 loop intermediate its ends and havingoneend connected with said Bourdon tube free end and its other endconnected with the pivot shaft of the pointer, the loop arranged toliein the plane of travel of said free end and-offset until the centerof gravity of the wire is in line with the points ofconnection of thetwo ends of the wire.

'2. The combination of claim 1 wherein the said wire is in the order of.020 inch diameter beryllium copper and the loop has a diameterapproximately one-half the distance between the connection ends of thewire:

3. The combination of claim 1 including a y-shaped n C? element movablein the plane of travel of said free end, one leg of the'U formed as achannel section receiving theifre e' end'of the'Bourdon tube forpressure sealing the same and for transmitting motion therefrom, theother leg .of the U. pivotally receiving one end of said wire, thechannel section extending beyond the Bourdon tube at both edges thereofand normal to the plane of movement of the said free end by amountsclearing the interior side walls of the housing close enough to preventexcessive movement of'said free end in directions normal to the plane ofpointer arm travel.

4. The combination of claim 3 including stop plates adjnstably fastenedto an interior side wall of the housing, spaced apart in the path of thesaid free end and cooperating with one of the channel section extensionstolimit' the travel of' the said free end in the plane of pointer armtravel.

5. The instrument of claim 1 wherein the scale plate has a longitudinalraised portion bearing the graduations projecting outwardly from thescale plate toward said removable window, and the said pointer movesin apath adjacent the raised portion, the pointer arm length such that thepointer path is not substantially nearer the window than is the saidraised scale portion whereby the pointer does not overlap thegraduations thus minimizing parallax.

6. In a measuring instrument for visually advising the value of avariable measurement, position, or the like; a'housing provided with ascale viewing portion, scale means viewable at said viewing portion, apressure receiving Bourdon tube in the housing having one end rigidlymounted to the housing and having the other end free for expansivemovement, an elongated pointer, a'pivot shaft for: the inner end portionof the pointer disposed between the ends of the Bourdon tube andarranged-for movement of the pointer in a plane parallel to that of theBourdon tube, a: driving connection between the free end of the Bourdontube and the pivot shaft of the pointer, said driving. connectionincluding a spring wire formed with a' complete loop intermediate itsends,"the loop being arranged to lie in the plane of pointerrotation andoffset to. an extent such that the center 'of gravity of the wire is inline with the points of connection of the two ends of the wire.

7. In a measuring instrument for visually advising the value ofavariable measurement, position, or the like;

" a housing provided with scale means, a pressure receiving;Bourdon tubein the housing having one end rigidly mountedtothe housing and havingthe other end free for expansive movement, an elongated pointer, a pivotshaftfor the inner' end portion of the pointer disposed between the endsof the Bourdon tube and arranged for movement of the pointer in avertical plane parallel to that of. theBourdon tube, ,a drivingconnection between the. free end of the Bourdon tube and the pivot shaftofthe pointer, said driving connection including a spring wireformed'with a complete loop intermediate its ends, the loop' beingarranged to lie in the plane of pointer rotation and offset 'to' anextent such that the center of gravity-of thewire'is in line with thepoints of connection of the two endsof the wire.

8. The combination of claim 7 in which the housing has opposed parallelwalls, the pointer pivot shaft extends perpendicularly to said 'walls,and a U-shaped element-liesdn the plane of theBourdon tube, saidU-shaped ele'menthaving one legzformed as a channel sectionreceivingrthefreeend of saidtube in pressuresealingrelation, and,the-other leg thereof connected with the adiacent end of the springwire.

9. The combination of claim 8 in which the said channel section hasopposite extensionsperpendicular to said said walls'and'engageabletherewith to limit movement of the free end of said "tube toward eitherside wall.

' '10..The combination of claim7 including a'hair spring means disposed'in a vertical plane and connected by its ends with the pivot shaft ofthe pointer and the housing 9 for taking up lost motion between thepointer and the pivot shaft.

11. In a measuring instrument responsive to a variable, the combinationcomprising, a pivoted indicating member having static balance about itspivot point, means responsive to a variable comprising a member movablein accordance with changes in the variable, a flexible resilient springwire having an intermediate helical loop operatively connected at itsends to said movable member and said indicating member respectively fortransmitting movement of the movable member representative of thevariable to said indicating member without the transmission ofextraneous vibratory movements.

12. In a measuring instrument responsive to a variable, the combinationcomprising, a pivoted statically balanced indicating member, a fluidpressure deformable member having an anchored end and a free end movablein accordance with changes in the variable, a flexible spring wireformed with a complete loop intermediate its ends and operativelyconnected at its ends to said deformable member and said indicatingmember respectively for transmitting movement of the deformable memberrepresentative of the variable to said indicating member without thetransmission of extraneous vibratory movements, said loop being offsetto an extent relative to the ends of said wire such that the center ofgravity of said wire is in line with the points of connection of the twoends of the wire with said deformable member and said indicating memberrespectively.

13. In a measuring instrument responsive to a variable, the combinationcomprising, a pivoted indicating memher, a fluid pressure deformablemember movable in accordance with changes in the variable and having afree end portion and an anchored end portion, an actuating connectionbetween the free end portion of said pressure deformable member and saidpivoted indicating memher, said actuating connection including a springWire having an intermediate helical loop positioned in coplanar relationto the end portions of said wire, and a manually adjustable meansforming part of said actuating connection for determining the relativeposition and motion between the free end portion of said deformablemember and said pivoted indicating member, the weight distribution ofsaid adjustable means and said pivoted indicating member about the pivotbeing such as to have static balance about the pivot.

References Cited in the file of this patent UNITED STATES PATENTS 9,163Bourdou Aug. 3, 1852 647,164 Staaf Apr. 10, 1900 1,616,628 Ingham Feb.8, 1927 2,017,183 Nutsford Oct. 15, 1935 2,267,056 Tracy Dec. 23, 19412,455,512 McCoy Dec. 7, 1948 V FOREIGN PATENTS 128,051 France Dec. 21,1878

